This invention relates to an improved process for obtaining .gamma.,.delta.-unsaturated carbonyl compounds by the reaction of a tertiary allyl alcohol with an acetal or ketal of an aliphatic aldehyde or ketone in the presence of an acid catalyst.
Heretofore, unsaturated carbonyl compounds have been prepared by using, as the acid catalyst, a strong acid, such as a mineral acid, a strong organic acid or a strong acid salt. See U.S. Pat. No. 3,453,317. The yields from such processes using a strong acid catalyst have been found, however, to be relatively low. For example, in Example 3 of the aforementioned patent, the reaction of the tertiary allyl alcohol, 3-methyl-1-buten-3-ol, with the ketal, acetone dimethyl ketal, in the presence of phosphoric acid provided yields of the .gamma.,.delta.-unsaturated ketone, 6-methyl-5-hepten-2-one, of only 54%.